1. Field of the Invention
The invention relates to aircraft in general and to lifting body aircraft in particular.
2. Prior Art
Lifting body aircraft are known in the art. The theory was pioneered by Dr. Alfred J. Eggers, Jr. who discovered that lift could be generated by modifying the shape of a blunt nose cone reentry vehicle. Eggers' theories led to several NASA and U.S. Air Force experimental aircraft in the 1960's and 1970's, namely the M2-F1, the M2-F2, the M2-F3, HL-10, X-24A and X-24B. Eggers' lift concept can also be seen in U.S. Pat. No. 3,276,722. All of these craft generate lift with the fuselage of the aircraft only; i.e. without a wing.
The Eggers craft can generally be described as conical sections. They have a blunt nose, swept back sides, round bottoms, and generally flat tops. As the crafts move through air, the high profile of their curved lower surfaces causes a significant amount of air to be displaced up and around the body of the vessel. This does two things. First, pressure is being exerted on the air mass at the interface with the hull. In response to this pressure, the air is compressed and it is displaced, up and around the lower surface of the craft. Air has viscosity, so it resists both the compression and the displacement. The greater the speed at which the craft is moving, the greater the resistance of the air. This resistance of the air is transmitted as force to its surroundings. Thus, the air pressure below the craft will be increased.
Second, a lift body is designed to move forward with its nose slightly elevated. As the craft moves forward, the craft will displace air, rarefying (reducing the density of) the air above the craft. This will result in a decrease in pressure above the upper surface of the lifting body.
The difference between the increased pressure generated on the lower surface and the decreased pressure at the upper surface will result in an overall upward force on the lifting body. This upward force is lift.
Although lift bodies were previously known, limited maneuverability and stability of many of the craft in atmospheric flight created significant challenges. Moreover, the inventors are not aware of any that were ever able to takeoff under their own power. Rather, previous lifting bodies were all believed to carried aloft by a winged aircraft and released to perform rocket powered maneuvers and then to return to earth at a glide. Accordingly, a lifting body craft meeting the following objectives is desired.